Recently, a storage system that handles large-scale data expands the functions of the storage system itself in order to store daily increasing large-capacity data in a large number of hard disk drives (HDD). Accordingly, the number of logical volumes formed in physical storage areas of the large number of hard disk drives is also increased. If the number of the logical volumes increases, it is necessary to also increase management information for managing the logical volumes. The management information of the logical volumes is normally stored in a semiconductor memory; however, the semiconductor memory has a small capacity and is expensive.
So, the management information of the logical volumes is stored in a RAID (Redundant Array of Inexpensive Disks) composed of low-price hard disk drives, thereby expanding the scale of the storage system at low cost (see Patent Literature 1).
Meanwhile, in a case of a storage system having a plurality of storage control devices, hard disk drives are accessed by each storage control device, so that access exclusion is required. Regarding a method of exclusive control between controllers, for example, there is a suggested method of allocating part of a cache memory and logical volumes to each controller and thereby eliminating exclusive control between controllers over the cache memory (see Patent Literature 2).